Low-{\Gamma} jets from Compact Binary Mergers as Candidate Electromagnetic Counterparts to Gravitational Wave Sources

TL;DR

This paper investigates low-{ extGamma} jets from compact binary mergers as potential electromagnetic counterparts to gravitational wave events, highlighting their properties, detection rates, and observational signatures.

Contribution

It introduces a Monte Carlo simulation approach to study low-{ extGamma} jets, revealing their prevalence and optical signatures as counterparts to GW sources.

Findings

78% of merger jets result in failed GRBs

Optical peaks range from 14-22 magnitude

Estimated detection rate of 2-3 per year

Abstract

Compact binary mergers, with neutron stars or neutron star and black-hole components, are thought to produce various electromagnetic counterparts: short gamma-ray bursts (GRBs) from ultra-relativistic jets followed by broadband afterglow; semi-isotropic kilonova from radioactive decay of r-process elements; and late time radio flares; etc. If the jets from such mergers follow a similar power-law distribution of Lorentz factors as other astrophysical jets then the population of merger jets will be dominated by low-{\Gamma} values. The prompt gamma-rays associated with short GRBs would be suppressed for a low-{\Gamma} jet and the jet energy will be released as X-ray/optical/radio transients when a shock forms in the ambient medium. Using Monte Carlo simulations, we study the properties of such transients as candidate electromagnetic counterparts to gravitational wave sources detectable by LIGO/Virgo. Approximately 78% of merger-jets result in failed GRB with optical peaks 14-22 magnitude and an all-sky rate of 2-3 per year.